Let’s Encrypt is leading Top SSL Issuers

Netrack reports some statistics for the Top SSL Issuers, and it’s nice to see Let’s Encrypt leading the race with a significant advantage over the rest. Well done, ladies and gentlemen!

HTTPS on Stack Overflow: The End of a Long Road

Way too often I hear rants from random people (unfortunately, many of them are also from the IT industry, with the deep understanding of the underlying issues) complaining about why company X or product Y doesn’t implement this or that feature.  As someone who has been involved a dozens, if not hundreds, of projects, I pretty much always can think of a number of reasons why even seemingly the simplest of features aren’t implemented for years.  These can vary from business side of things – insufficient budgets, strategic goals, and the like – to technical, such as architectural limitations, insufficient expertise, insufficient resources, etc.

One of the recent frequent rant that keeps coming up is “Why don’t they just enable HTTPS?”.  Again, as someone being involved in HTTPS setup for several different environments I can think of a number of reasons why.  SSL certificates used to cost money and were quite cumbersome to install until very recently.  Thanks to Let’s Encrypt effort, SSL certificates are now free and quite easy to issue and renew.  But that’s only part of the problem.  Enabling HTTPS requires infrastructural changes, and the more complex your infrastructure, the more changes are needed.  Just think of a few points here – web server configuration (especially when you have multiple web servers, with varied software (Apache, Nginx, IIS) and varied versions of that software), load balancers, web application firewalls, reverse proxies, caching servers, and so on.

Apart from the infrastructural changes, HTTPS often needs changes on the application level.  Caching, cookies, headers, making sure that all your resources are HTTPS-only, redirects, and the like.

All of the above issues are multiplied by a gadzillion, when your project is publicly available, used by tonnes of people, and provides embeddable content or APIs to third-party (hello, backward compatibility).

This is not to mention that HTTPS itself is a complex subject, not well understood by even the most experienced system administrators and developers.  There are different protocols and versions (SSL vs. TLS), cipher suites, handshakes, and protocol details.  Just have a look at the variety of checks and the report length done by Qualys’ SSL Labs Server Test.  Even giants like Google, who employ thousands of smart people, can’t get it all right.

But for some reason, people either don’t know or prefer to ignore all this complexities, and whine and cry anyway.

Recently, Stack Overflow – a well known collection of sites on a variety of technical subjects, has completed the migration to HTTPS everywhere.  These are also people with a lot of knowledge and expertise and with access to all the information.  Just have a look at their long way, which took not months, but years: HTTPS on Stack Overflow: The End of a Long Road.

Today, we deployed HTTPS by default on Stack Overflow. All traffic is now redirected to https:// and Google links will change over the next few weeks. The activation of this is quite literally flipping a switch (feature flag), but getting to that point has taken years of work. As of now, HTTPS is the default on all Q&A websites.

We’ve been rolling it out across the Stack Exchange network for the past 2 months. Stack Overflow is the last site, and by far the largest. This is a huge milestone for us, but by no means the end. There’s still more work to do, which we’ll get to. But the end is finally in sight, hooray!

So next time you are about to start crying about somebody not having feature X or Y, just give it a minute first.  Try to imagine what goes on on the other side.  You aren’t the only one with low budgets, pressing deadlines, insufficient knowledge, bad colleagues and horrible bosses…

Using the Strict-Transport-Security header

Julia Evans has an excellent write-up on “Using the Strict-Transport-Security header” – what it is, why you’d want to use it, and what are some of the consequences of using one.

As always with her blog posts, this one is very focused on one particular subject, easy to read, and explains things simply, so that the reader’s technical level is always irrelevant (OK, OK, you do need a basic understanding of how HTTP works, but not more than that).


HAProxy SNI” is pure gold! If you want to have a load balancer for HTTPS traffic, without managing SSL certificates on the said load balancer, there is a way to do so.

The approach is utilizing the Server Name Indication (SNI) extension to the TLS protocol.  I knew about it and I was already using it on the web server side, but it didn’t occur to me that it’ll be utilized on the load balancer.  Here’s the configuration bit:

frontend https *:443
  description Incoming traffic to port 443
  mode tcp
  tcp-request inspect-delay 5s
  tcp-request content accept if { req_ssl_hello_type 1 }
  use_backend backend-ssl-foobar if { req_ssl_sni -i foobar.com }
  use_backend backend-ssl-example if { req_ssl_sni -i example.com }
  default_backend backend-ssl-default

The above will make HAProxy listen on port 443, and then send all traffic for foobar.com to one backend, all traffic for example.com to another backend, and the rest to the third, default backend.

Fixing outdated Let’s Encrypt (zope.interface error)

I’ve started using Let’s Encrypt for the SSL certificates a while back.  I installed it on all the web servers, irrelevant of the need for SSL, just to have it there, when I need it (thanks to this Ansible role).  One of those old web servers needed an SSL certificate recently, so I thought it’d be no problem to generate one.

But I was wrong. The letsencrypt-auto tool got outdated and was failing to execute, throwing some Python exception about missing zope.interface module.  A quick Google search brought this StackOverflow discussion, with the exact issue I was having.

Traceback (most recent call last):
  File "/root/.local/share/letsencrypt/bin/letsencrypt", line 7, in <module>
    from certbot.main import main
  File "/root/.local/share/letsencrypt/local/lib/python2.7/dist-packages/certbot/main.py", line 12, in <module>
    import zope.component
  File "/root/.local/share/letsencrypt/local/lib/python2.7/dist-packages/zope/component/__init__.py", line 16, in <module>
    from zope.interface import Interface
ImportError: No module named interface

However, the solution didn’t fix the problem for me:

/opt/letsencrypt/letsencrypt-auto -v

Even pulling the updated version from the GitHub repository didn’t solve it.

After poking around for a while more, I found this bug report from the last year, which solved my problem.

I recommend:

  1. Running rm -rf /root/.local/share/letsencrypt. This removes your installation of letsencrypt, but keeps all configuration files, certificates, logs, etc.
  2. Make sure you have an up to date copy of letsencrypt-auto. It can be found here.
  3. Run letsencrypt-auto again.

If you get the same behavior, you can try installing zope.interface manually by running:

/root/.local/share/letsencrypt/bin/pip install zope.interface

Hopefully, next time I’ll remember to search my blog’s archives …

Update (May 31, 2017): check out my brother’s follow up post with even better way of fixing this issue.